On 18/12/17 08:43, Emanuel Berg wrote:
It seems after putting on a new chain, it turns
really slack after only 2-3 weeks. When you
then restraighten it, it remains tight
considerably longer. Is this so or does
intuition play a trick on me? In general, how
many bike hours does a chain last?


2-3 weeks seems like only a short amount of time under "normal"
conditions. There are too many variables to quantify exactly "how long".

Is it possible the rear axle nuts were simply not done up quite tight
enough and the axle slipped forward in the drop out slots?

I'd expect at least 2000-6000km from a new chain to wear 1%, depending
on the conditions and the rider. The Wippermann chain test shows more
than a 3:1 wear rate from the best to worst chains they tested. (36 to
114 hours of their abusive test.)

http://www.cantitoeroad.com/Wipperma...ained_b_2.html

Standard bicycle chains measure 1/2 inch from pin centre to pin centre.
There are something close to 100 half links or 50 inches of chain, so 1%
is one half link or 1/2 inches of wear. That would mean the rear wheel
would need to be moved 1/4 inches rearward to take up the slack from a
worn out chain.

(Actual number of links or half links depends on the length of chain
stays and the crank and hub gear diameters.)

--
JS